Essential oil compositions



Patented June 10, 1947 ESSENTIAL OIL COMPOSITIONS Walter A. Taylor, Killingworth, Conn., assignor to Atlas Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Application February 21, 1942, Serial No. 431,819

17 Claims.

The present invention relates to improvements in essential oil compositions.

An object of the invention is to provide clear extended compositions of essential oils.

Another object is to provide a composition of an essential oil and a miscible solubilizing or dispensing'material which composition is stable and capable of dilution with water to form solutions or dispersions of the essential oil in water.

A further object is to provide a solution or dispersion of essential oil in water.

The above and other objects will become apparent in the course of the following description.

Essential oils comprise a wide variety of flavoring, perfuming and medicinal materials. The various essential oils have in common, in addition to their characteristic ability to be distilled, the property of being virtually insoluble and very difllcultly dispersible in water. Furthermore, the effects of the essential oils as regards taste and odor are obtainable to best advantage when the essential oil is at a great dilution. Many of the essential oils used in flavoring and perfumery do not produce pleasant sensations at all until they are diluted to a very considerable extent. These facts are all well-known, and they have led to the use of a number of means for extending, diluting and dispersing these oils in various media. Many of the oils have been diluted with large quantities of alcohol and distributed in this form. Instead of alcohol, other solvents, such as ethyl glycerine, glycols, isopropyl alcohol, and similar compounds, have been used for the purpose of extending and solubilizing the essential oils. For the preparation of aqueous dispersions or solutions there have also been used a number of the usual emulsifying and dispersing agents. These materials have various ob jections, such as undesirable odors or tastes of their own, undesirably high toxicity, expense either due to the cost of the material or due to the large amount of material that must be used, and inability to produce satisfactory aqueous solutions or dispersions of the oils.

I have now found that compounds of a certain class are miscible with essential oils to form clear extended solutions which can be used as such, or these solutions can be diluted with water to form stable dispersions-or solutions of the essential oils. Alternatively, aqueous dispersions or solutions can be prepared by the use of these compounds without first preparing solutions of the essential oil in the compound. The compounds which I contemplate using can be defined as water-soluble hydroxy polyoxyethylene ethers of partial higher fatty acid esters of low molecular weight polyhydroxylic compounds. By low molecular weight polyhydroxylic compounds," I mean to include compounds which have two or more hydroxyl groups and whose molecular weight is' not greater than that of the oligosaccharides. Preferred polyhydroxylic compounds of this class are the polyhydric alcohols such as ethylene glycol, glycerol, pentaerythritol; hexitols, such as mannitol and sorbitol; the internal ethers of polyhydric alcohols, such as hexitans, for example, mannitan and sorbitan, and hexides, for example, sorbide and mannide; and the external ethers of the polyhydric alcohols, such as polyglycerols and dipentaerythritol. Of the preferred group the hexitans have been found best. In addition to these preferred polyhydroxylic compounds, I can also use others of the broad group, such as the sugars like glucose and sucrose, cyclitols, such as inositol, and

others which will be apparent. As the fatty acid I can use any of the aliphatic monocarboxylic acids with not less than 10 carbon atoms, but preferably I use the fatty acids with from 12 to 18 carton atoms and those with from 12 to 16 carbon atoms are best.

As stated in the definition, the compounds which I use are hydroxy polyoxyethylene ethers of partial esters. That is, the fatty acid group should be attached directly to the polyhydroxylic compound as distinguished from a compound in which the fatty acid is at the end of a long polyoxyethylene chain. The partial esters themselves are either completelyor virtually insoluble in water. However, by adding a sufiicient number of oxyethylene units or groups to the unesterified hydroxyls of the partial esters, the resulting compound becomes water-soluble. The number of oxyethylene units required to render a particular compound water-soluble is dependent upon the length of the fatty acid chain and upon the number of fatty acid groups in the molecule. Thus, a stearate requires more oxyethylene units to solubilize it than does a laurate. Similarly, a diester requires about twice as many syethylene units to solubilize it than does a lonoester. A more complete description of these henomena is to be found in the application of Dbl't 8. Rose, Serial Number 371,829, filed lecember 26. 1940, for Hydroxy-polyoxyethylne ethers." The Rose invention is specific to exitan and hexide derivatives but the disclosure ith regard to the relation of fatty acid chain :ngth and degree of esterification to the numer of oxyethylene units required to produce 'ater-solubility is broadly applicable-to all of :1e compounds that are useful in the present ivention. In general the water-soluble hydroxy olyoxyethylene ethers require at least the numer of oxyethylene units called for by the formula where n is the number of oxyethylene groups and I is the number of carbon atoms in the fatty cid.

I have found that the water-soluble hydroxy )olyoxyethylene ethers which have from 6 to lbout 60 oxyethylene units per mol are satisfacory for my purposes. Within this range the preerred compounds are those with from 12 to about i0 oxyethylene units per mol. It will be under- :tood that these numerical values may be avertge values in a mixed'product. The preferred roducts, as commercially prepared, are mixtures )f a number of compounds of varying oxyethylene :hain lengths, the average of which is in the range stated above.

The hydroxy polyoxyethylene ethers can be nade in a number of different ways which will )e apparent to those skilled in the art. I prefer, iowever, first to make the partial ester by a :ustomary esterification procedure and then reict the partial ester with ethylene oxide in the aresence of an alkaline catalyst, such as sodium nethylate. To prepare the hexitan and hexide esters it is preferable to react a hexitol and the :atty acid, (or fat; or oil) under high temperature :onditions which produce anhydridization of the riexitol to the hexitan or hexide concurrently with the esterification. I have found that the products made in this way have a useful heterogeneity which makes them more efiicient as soluailizing and dispersing agents for essential oils.

Example A A typical ether for use in practicing the present invention can be prepared as follows:

An ester product of cyclic inner ethers derivable from mannitol and palmitic acid was prepared by reacting mannitol and palmitic acid in a. mol-for-mol ratio at 240 C. in an inert atmosphere and with 0.05% NaOH as catalyst. The resulting product had a hydroxy] value of 355 and ester value of 146. It melted at about 40 C.

lbs. of this product were melted and intro duced into a stirring autoclave. Heat was applied and when the temperature reached C., 72.5 g. dry sodium methylate were added as catalyst. I 7

Heating was continued and, when the temperature reached 110 C., introduction of liquid ethylene oxide was started. In the course of 2.5 hours, 176 lbs. ethylene oxide were added, the temperature being controlled within the range'of to C. by the use of a cooling coil in the autoclave. The temperature was maintained at 105-110" C. until the ethylene oxide was consumed as indicated by return of the pressure to atmospheric.

clave it had dark color and noticeable odor. Furthermore, it contained a small amount of sodium soap produced from the catalyst.

This product was then further processed by transferring it to a vacuum kettle and blowing for 30 minutes with superheated steam at C. and 10 mm. pressure while agitating. 2% activated carbon were added and heating continued another 15 minutes after which the batch was filtered. The product was then of light color and free from obj ectionable odor.

The weights of reactants in the autoclaving reaction correspond to 20 mols ethylene oxide to 1 mol ester (calculated for mannitan monopalmitate, the predominating ester).

This invention is broadly applicable to essential oils asa class, both natural and synthetic types. Representative members of this class which I have employed in my. invention are benzaldehyde, eucalyptol, oil or orange, terpineol, oil of spearmint, oil of lemon, oil of cassia, oil of clove, oil of cedar leaf. oil of peppermint, tea tree oil, oil of Chenopodium, Siberian pine needle oil, methyl salicylate, benzyl acetate.

The composition of essential oil and hydroxy polyoxyethylene ether is prepared by dissolving the essential oil in a quantity of the ether. of the hydroxy polyoxyethylene ethers are very viscous or soft solids at room temperature and in such cases they should be warmed to liquiiy them before dissolving the essential oil therein. The essential oils and said ethersare soluble in each other so that compositions of varying concentrations can be made.

The compositions of essential oil and ether are clear, extended essential oil solutions which can be kept for an indefinite period without separation. In this form the compositions are highly useful for flavoring, perfuming, or the like. The ethers are not volatile and actually dissolve and hold the essential oil, reducing its volatility.

Many of the extended essential oil compositions are to be used to introduce the essential oil into aqueous media. To produce stable fine dispersions or solutions the extended compositions should have at least as much of the hydroxy polyoxyethylene ether as essential oil and preferably several times as much ether as essential oil. For example, a composition containing 4 to 6 or more parts of the ether to 1 part of essential oil is useful in preparing a highly diluted aqueous dispersion or solution of the oil.

Aqueous dispersions or solutions of essential oils can be made also by mixing the hydroxy polyoxyethylene ether, the essential oil and the water in various sequences without first making a solution of the essential oil in the ether.

The compositions of the invention find application wherever the essential oils are needed or customarily employed. Flavoring concentrates are useful in the customary way in cooking and candy-making practice. Perfume and deodorant oils are useful for making toilet waters, cosmetics. laundry aids, and the like. A modern use for the perfume oil compositions is in the field of socalled theater sprays. in which the essential oil dispersed in water is sprayed either into the air stream of an air-conditioning system or freely into the theater.

The following examples are illustrative of extended essential oil compositions that can be made according to the inventions. In each case Some 1 the essential oil and solvent indicated were mixed forming clear solutions. The solvents were all liquids at room temperature with the exception of the ethylene glycol derivative used in Examples 24 and 25. In the case of these-two examples the ingredients were warmed above the melting point of the solvent before mixing.

6 parent to those skilled in the art. It will be understood that mixtures of different essential oils can be used in these compositions and also that other ingredients besides essential oils can be incliideld to prepare various types of useful articles.

aim:

1. A composition comprising a clear, stable soifig g Essential 011 Parts lv n Part Benzaldehyde 1 Mlgmlta i) monolaura hydroxy polyoxyethylene ether oxyethylena groups r mo 1 -do 1 .do... 1 d l 1 l 1 1 Oil oi Peppermlnt. 1 Tea Tree Oil (Ti-tree) 1 Siberian Pine Needle 011...- 1 Methyl Sailcylate. 1 Benzyl Acetate. l i 11 4 Mannitan monopalmite hydroxy poiyoxyethylene ether (20 oxyethylene groups Oil of Cassia Oil of Orange Oil of Cassiaper mol).

- per moi). 21 Oil of Orange 1 d 22 Oil of Cassia l per in Oil of Orange". 1 o 011 of Cassia.

Oil oi Orange 1 .do 1

do l perm 29 do 1 0.........

per m Pentaerythritol monoiaurate hydroxy poiyoxyethyiene ether (20 oxyethylene grgups per moi) Glycerol mouolaurate hydroxy poiyoxyethylene ether (20 oxyethylene groups do Glycerol monooieate hydroxy polyoxyethyiene ether (20 oxyethylene groups o Glycerol 11)nonoslearate hydroxy polyoxyethyiene ether (20 oxyethylene groups 0 .d 1 Ethylene glycol monoiaurate hydroxy poiyoxyethylene ether (20 oxyethyiene grgups per mol). o Sorbi1t)an monolaurate hydroxy polyoxyethylene ether (8 oxyethyiene groups per mo v Sorbitan 1monolaurate hydroxy poiyoxyethylene ether (20 oxyethyiene groups rmo annitan monoiaurate hydroxy poiyoxyethyiene ether (60 oxyethyiene groups The following examples are illustrative of 40 lution of a quantity of an essential oil and at aqueous dispersions or solutions of essential oils in accordance with the invention. In each case a solution of essential oil and solvent was made first and then mixed thoroughly with the water.

least an equal quantity of a water-soluble 'hydroxy polyoxyethylene ether of a partial higher fatty acid ester of a low molecular weight polyhydroxylic compound, the said solution being cagg gl Essential oil Parts Solvent Parts ggg Character of dispersion Oil of Orange..- 1 Mannitan monoiaurate hydroxy polyoxyethylene 4 95 Cloudy but stable.

ether (20 oxyethylene groups per mo do- 1 do.-- 6 93 Slightly cloudy but stable.

Oil of Cass1a 1 do 7 7 9 Clear. Oil of Orange.-.. 1 6 9 Do. Oil of Cassia 1 Glycerol monolaurate hydroxy polyoxyethylene 7 9 Do.

' ether (20 oxyethyiene groups per mol).

Example pable, upon dilution w1th water, of forming a 1 part of oil of orange was shaken with 9 parts of water. 6 parts of mannitan monolaurate hydroxy poiyoxyethylene ether (20 oxyethylene units per mol) were slowly added with agitation. When first prepared the composition was a slightly turbid stable dispersion which became clear on standing for 5 days.

Example 36 A mixture of 1 part of oil of orange and 9 parts 7 of water was agitated and to this 3 parts of mannitan monolaurate hydroxy polyoxyethylene.

ether (20 oxyethylene units per mol) were added and thoroughly mixed. Finally another 3 parts oi the same ether were added and thoroughly mixed in the composition. The resulting composition was clear and stable.

From the foregoing description and examples many other essential oil compositions will be aplution of a quantity of an essential oil in at least an equal quantity of a water-soluble hydroxy polyoxyethylene ether of a partial ester of a fatty acid with from 12 to 18 carbon atoms and a low molecular weight polyhydroxylic compound selected from the group consisting of polyhydric alcohols and polyhydric internal and external ethers thereof, the said solution being capable, upon dilution with water, of forming a clear, stable aqueous dispersion of said essential oil and hydroxy polyoxyethylene ether.

5. A composition comprising a clear, stable solution of a quantity of an essential oil and at leastan equal quantity of a water-soluble hydroxy polyoxyethylene ether of a partial ester 01 a hexitan with a fatty acid with from 12 to 16 carbon atoms, said hydroxy polyoxyethylene ether having from 6 to 60 oxyethylene units per mol, the said solution being capable, upon dilution with water, of forming a clear, stable aqueous dispersion of said essential oil and. hydroxy polyoxyethylene ether.

6. A flavoring composition comprising a clear, stable solution of a quantity of flavoring essential oil and at least 4 times thesaid quantity of a water-soluble polyoxyethylene ether of a partial higher fatty acid ester of a. low molecular weight polyhydroxylic compound, the said solution being capable, upon dilution with water, of forming a clear, stable aqueous dispersion of said essential oil and hydroxy polyoxyethylene ether.

7. A perfuming composition comprising a clear, stable solution of a quantity of a perfuming essential oil and at least 4 times the said quantity of a water-soluble hydroxy polyoxyethylene ether of a partial higher fatty acid ester of a low molecular weight polyhydroxylic compound, the said solution being capable, upon dilution with water, of forming a clear, stable aqueous dispersion of said essential oil and hydroxy polyoxyethylene ether.

8. A composition comprising a clear, stable aqueous dispersion of a quantity of an essential oil and a larger quantity of a water soluble hydroxy polyoxyethylene ether of a partial higher fatty acid ester of a low molecular weight polyhydroxylic compound.

9. A composition as in claim 8 wherein the fatty acid has from 12 to 18 carbon atoms and the polyhydroxylic compound is selected from the group consisting of polyhydric alcohols and the internal and external ethers'thereof.

10. A composition comprising a clear, stable aqueous dispersion of a quantity of an essential oil and at least an equal quantity of a water-soluble hydroxy p'olyoxyethylene ether of a hexitan partial ester of a fatty acid with from 12 to 16 carbon atoms, said ether having from 12 to 50 oxyethylene groups per mol.

11. A clear, stable aqueous dispersion of a quantity of an essential oil and a larger quantity of a water-soluble hydroxy polyoxyethylene ether of a partial ester of a fatty acid with from 12 to 18 carbon atoms and a low molecular weight polyhydroxylic compound, said ether having from 12 to 50 oxyethylene units per mol.

12. A dispersion as in claim 11 wherein the said hydroxy polyoxyethylene ether is present in a quantity at least 4 times the quantity or said essential oil.

13. A composition comprising a clear, stable sosaid essential oil and hydroxy polyoxyethylene ether.

14. A composition comprising a clear, stable solution of a quantity oi. an essential oil and at least an equal quantity of mannitan monolaurate hydroxy polyoxyethylene' ether with about 20 oxyethylene units per mol. the said solution being capable, upon dilution with water, of forming a clear, stable aqueous dispersion of said essential oil and hydroxy polyoxyethylene ether.

15. A composition comprising a. clear, stable solution of a quantity of an essential-oil and at least an equal quantity of a sorbitan monolaurate hydroxy polyoxyethylene ether with from 8 to oxyethylene units per mol. the said solution being capable, upon dilution with water, of forming a clear, stable aqueous dispersion of said essential oil and hydroxy polyoxyethylene ether.

16. A composition comprising a clear, stable solution of a quantity of an essential oil and at least an equal quantity of a water soluble hexitan monopalmitate hydroxy polyoxyethylene v ether, the said solution being capable, upon dilution with water, of forming a clear, stable aqueous dispersion of said essential oil and hydroxy polyoxyethylene ether.

17. A composition comprising a clear, stable solution of a quantity of an essential oil and at leastan equal quantity of mannitan monopalmitate hydroxy polyoxyethylene ether with about 20 oxyethylene units per mol, the said solution being capable, upon dilution with water, of forming a clear, stable aqueous dispersion of said essential oil and hydroxy polyoxyethylene ether.

WALTER A. TAYLOR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,959,930 Schmidt et a1 May 22, 1934 1,970,578 Schoeller et a1 Aug. 21, 1934 2,230,517 Cahn et al. Apr. 1, 1941 

